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 * Copyright (c) 1998, 2013, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
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package javax.swing.text.html.parser;

import javax.swing.text.SimpleAttributeSet;
import javax.swing.text.html.HTMLEditorKit;
import javax.swing.text.html.HTML;
import javax.swing.text.ChangedCharSetException;

import java.util.*;
import java.io.*;
import java.net.*;

/**
 * A Parser for HTML Documents (actually, you can specify a DTD, but
 * you should really only use this class with the html dtd in swing).
 * Reads an InputStream of HTML and
 * invokes the appropriate methods in the ParserCallback class. This
 * is the default parser used by HTMLEditorKit to parse HTML url's.
 * <p>This will message the callback for all valid tags, as well as
 * tags that are implied but not explicitly specified. For example, the
 * html string (&lt;p&gt;blah) only has a p tag defined. The callback
 * will see the following methods:
 * <ol><li><i>handleStartTag(html, ...)</i></li>
 * <li><i>handleStartTag(head, ...)</i></li>
 * <li><i>handleEndTag(head)</i></li>
 * <li><i>handleStartTag(body, ...)</i></li>
 * <li><i>handleStartTag(p, ...)</i></li>
 * <li><i>handleText(...)</i></li>
 * <li><i>handleEndTag(p)</i></li>
 * <li><i>handleEndTag(body)</i></li>
 * <li><i>handleEndTag(html)</i></li>
 * </ol>
 * The items in <i>italic</i> are implied, that is, although they were not
 * explicitly specified, to be correct html they should have been present
 * (head isn't necessary, but it is still generated). For tags that
 * are implied, the AttributeSet argument will have a value of
 * <code>Boolean.TRUE</code> for the key
 * <code>HTMLEditorKit.ParserCallback.IMPLIED</code>.
 * <p>HTML.Attributes defines a type safe enumeration of html attributes.
 * If an attribute key of a tag is defined in HTML.Attribute, the
 * HTML.Attribute will be used as the key, otherwise a String will be used.
 * For example &lt;p foo=bar class=neat&gt; has two attributes. foo is
 * not defined in HTML.Attribute, where as class is, therefore the
 * AttributeSet will have two values in it, HTML.Attribute.CLASS with
 * a String value of 'neat' and the String key 'foo' with a String value of
 * 'bar'.
 * <p>The position argument will indicate the start of the tag, comment
 * or text. Similar to arrays, the first character in the stream has a
 * position of 0. For tags that are
 * implied the position will indicate
 * the location of the next encountered tag. In the first example,
 * the implied start body and html tags will have the same position as the
 * p tag, and the implied end p, html and body tags will all have the same
 * position.
 * <p>As html skips whitespace the position for text will be the position
 * of the first valid character, eg in the string '\n\n\nblah'
 * the text 'blah' will have a position of 3, the newlines are skipped.
 * <p>
 * For attributes that do not have a value, eg in the html
 * string <code>&lt;foo blah&gt;</code> the attribute <code>blah</code>
 * does not have a value, there are two possible values that will be
 * placed in the AttributeSet's value:
 * <ul>
 * <li>If the DTD does not contain an definition for the element, or the
 * definition does not have an explicit value then the value in the
 * AttributeSet will be <code>HTML.NULL_ATTRIBUTE_VALUE</code>.
 * <li>If the DTD contains an explicit value, as in:
 * <code>&lt;!ATTLIST OPTION selected (selected) #IMPLIED&gt;</code>
 * this value from the dtd (in this case selected) will be used.
 * </ul>
 * <p>
 * Once the stream has been parsed, the callback is notified of the most
 * likely end of line string. The end of line string will be one of
 * \n, \r or \r\n, which ever is encountered the most in parsing the
 * stream.
 *
 * @author Sunita Mani
 */
public class DocumentParser extends javax.swing.text.html.parser.Parser {

  private int inbody;
  private int intitle;
  private int inhead;
  private int instyle;
  private int inscript;
  private boolean seentitle;
  private HTMLEditorKit.ParserCallback callback = null;
  private boolean ignoreCharSet = false;
  private static final boolean debugFlag = false;

  public DocumentParser(DTD dtd) {
    super(dtd);
  }

  public void parse(Reader in, HTMLEditorKit.ParserCallback callback, boolean ignoreCharSet)
      throws IOException {
    this.ignoreCharSet = ignoreCharSet;
    this.callback = callback;
    parse(in);
    // end of line
    callback.handleEndOfLineString(getEndOfLineString());
  }

  /**
   * Handle Start Tag.
   */
  protected void handleStartTag(TagElement tag) {

    Element elem = tag.getElement();
    if (elem == dtd.body) {
      inbody++;
    } else if (elem == dtd.html) {
    } else if (elem == dtd.head) {
      inhead++;
    } else if (elem == dtd.title) {
      intitle++;
    } else if (elem == dtd.style) {
      instyle++;
    } else if (elem == dtd.script) {
      inscript++;
    }
    if (debugFlag) {
      if (tag.fictional()) {
        debug("Start Tag: " + tag.getHTMLTag() + " pos: " + getCurrentPos());
      } else {
        debug("Start Tag: " + tag.getHTMLTag() + " attributes: " +
            getAttributes() + " pos: " + getCurrentPos());
      }
    }
    if (tag.fictional()) {
      SimpleAttributeSet attrs = new SimpleAttributeSet();
      attrs.addAttribute(HTMLEditorKit.ParserCallback.IMPLIED,
          Boolean.TRUE);
      callback.handleStartTag(tag.getHTMLTag(), attrs,
          getBlockStartPosition());
    } else {
      callback.handleStartTag(tag.getHTMLTag(), getAttributes(),
          getBlockStartPosition());
      flushAttributes();
    }
  }


  protected void handleComment(char text[]) {
    if (debugFlag) {
      debug("comment: ->" + new String(text) + "<-"
          + " pos: " + getCurrentPos());
    }
    callback.handleComment(text, getBlockStartPosition());
  }

  /**
   * Handle Empty Tag.
   */
  protected void handleEmptyTag(TagElement tag) throws ChangedCharSetException {

    Element elem = tag.getElement();
    if (elem == dtd.meta && !ignoreCharSet) {
      SimpleAttributeSet atts = getAttributes();
      if (atts != null) {
        String content = (String) atts.getAttribute(HTML.Attribute.CONTENT);
        if (content != null) {
          if ("content-type"
              .equalsIgnoreCase((String) atts.getAttribute(HTML.Attribute.HTTPEQUIV))) {
            if (!content.equalsIgnoreCase("text/html") &&
                !content.equalsIgnoreCase("text/plain")) {
              throw new ChangedCharSetException(content, false);
            }
          } else if ("charset"
              .equalsIgnoreCase((String) atts.getAttribute(HTML.Attribute.HTTPEQUIV))) {
            throw new ChangedCharSetException(content, true);
          }
        }
      }
    }
    if (inbody != 0 || elem == dtd.meta || elem == dtd.base || elem == dtd.isindex
        || elem == dtd.style || elem == dtd.link) {
      if (debugFlag) {
        if (tag.fictional()) {
          debug("Empty Tag: " + tag.getHTMLTag() + " pos: " + getCurrentPos());
        } else {
          debug("Empty Tag: " + tag.getHTMLTag() + " attributes: "
              + getAttributes() + " pos: " + getCurrentPos());
        }
      }
      if (tag.fictional()) {
        SimpleAttributeSet attrs = new SimpleAttributeSet();
        attrs.addAttribute(HTMLEditorKit.ParserCallback.IMPLIED,
            Boolean.TRUE);
        callback.handleSimpleTag(tag.getHTMLTag(), attrs,
            getBlockStartPosition());
      } else {
        callback.handleSimpleTag(tag.getHTMLTag(), getAttributes(),
            getBlockStartPosition());
        flushAttributes();
      }
    }
  }

  /**
   * Handle End Tag.
   */
  protected void handleEndTag(TagElement tag) {
    Element elem = tag.getElement();
    if (elem == dtd.body) {
      inbody--;
    } else if (elem == dtd.title) {
      intitle--;
      seentitle = true;
    } else if (elem == dtd.head) {
      inhead--;
    } else if (elem == dtd.style) {
      instyle--;
    } else if (elem == dtd.script) {
      inscript--;
    }
    if (debugFlag) {
      debug("End Tag: " + tag.getHTMLTag() + " pos: " + getCurrentPos());
    }
    callback.handleEndTag(tag.getHTMLTag(), getBlockStartPosition());

  }

  /**
   * Handle Text.
   */
  protected void handleText(char data[]) {
    if (data != null) {
      if (inscript != 0) {
        callback.handleComment(data, getBlockStartPosition());
        return;
      }
      if (inbody != 0 || ((instyle != 0) ||
          ((intitle != 0) && !seentitle))) {
        if (debugFlag) {
          debug("text:  ->" + new String(data) + "<-" + " pos: " + getCurrentPos());
        }
        callback.handleText(data, getBlockStartPosition());
      }
    }
  }

  /*
   * Error handling.
   */
  protected void handleError(int ln, String errorMsg) {
    if (debugFlag) {
      debug("Error: ->" + errorMsg + "<-" + " pos: " + getCurrentPos());
    }
        /* PENDING: need to improve the error string. */
    callback.handleError(errorMsg, getCurrentPos());
  }


  /*
   * debug messages
   */
  private void debug(String msg) {
    System.out.println(msg);
  }
}
